Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in women. However, we are currently unable to identify women early in their adult life who are at high risk of CVD. The American Heart Association has suggested that pregnancy complications be used to distinguish high-risk women in order to monitor and control CVD risk factors. Preterm delivery may act as an important early clinical marker of CVD risk. Prior studies have shown a two to three fold increased risk of CVD in women who delivered a child preterm, but these studies lack data on pre-pregnancy risk factors, such as diet, smoking, body mass index (BMI), physical activity, and family history of CVD. We will utilize the rich data of the Nurses' Health Study II to characterize the association between preterm delivery and risk of CVD in mothers as well as the predictive utility of preterm delivery. We first hypothesize that preterm delivery increases risk of CVD events, including myocardial infarction, stroke, and coronary revascularization surgery, independent of pre-pregnancy risk factors such as family history of CVD, BMI, diet, smoking, physical activity, and family history of CVD. We also hypothesize that this association remains evident in pregnancies not complicated by hypertensive disorders or gestational diabetes mellitus. We will next evaluate the incidence, timing and severity of CVD risk factors as they emerge after preterm delivery, including overweight and obesity, hypertension, hypercholesterolemia, and type II diabetes mellitus. We further hypothesize that the increased risk of CVD associated with preterm delivery is mediated, but only in part, by CVD risk factors that emerge after a preterm pregnancy. Finally, we will evaluate whether inclusion of preterm delivery into risk prediction scores improve Receiver Operator Characteristic curves and net reclassification for the prediction of CVD. This project will allow us to determine the natural history of CVD risk as it evolves after a preterm pregnancy so that we can utilize pregnancy history to better predict and prevent CVD in women.